<?
    class PrincipioLab_Comparator_DefaultSingleton
    {
        private static $instance = null;

        private function __construct() {}

        public static function getInstance()
        {
            if (is_null(self::$instance))
                self::$instance = new PrincipioLab_Comparator_Default();

            return self::$instance;
        }
    }
?>